scholarly journals A method to estimate the number of neurons supporting visual orientation discrimination in primates

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 1752
Author(s):  
Ruben Coen-Cagli ◽  
Ingmar Kanitscheider ◽  
Alexandre Pouget
Keyword(s):  
Visual Cortex ◽  
Ganglion Cells ◽  
Visual Pathway ◽  
Orientation Discrimination ◽  
Visual Orientation ◽  
Retinal Ganglion ◽  
V1 Neurons ◽  
Similar Information ◽  
Physiological Information ◽  
Specific Experiment

In this method article, we show how to estimate of the number of retinal ganglion cells (RGC), and the number of lateral genicular nucleus (LGN) and primary visual cortex (V1) neurons involved in visual orientation discrimination tasks. We reported the results of this calculation in Kanitscheider et al. (2015), where we were interested in comparing the number of neurons in the visual periphery versus visual cortex for a specific experiment. This calculation allows estimation of the information content at different stages of the visual pathway, which can be used to assess the efficiency of the computations performed. As these numbers are generally not readily available but may be useful to other researchers, we explain here in detail how we obtained them. The calculation is straightforward, and simply requires combining anatomical and physiological information about the macaque visual pathway. Similar information could be used to repeat the calculation for other species or modalities.

scholarly journals Targeted comodulation supports flexible and accurate decoding in V1

2021 ◽  
Author(s):  
Caroline Haimerl ◽  
Douglas A. Ruff ◽  
Marlene R. Cohen ◽  
Cristina Savin ◽  
Eero P. Simoncelli
Keyword(s):  
Orientation Discrimination ◽  
Physiological Data ◽  
Visual Orientation ◽  
Strongly Correlated ◽  
Neural Responses ◽  
Stimulus Information ◽  
Behavioral Task ◽  
V1 Neurons ◽  
Stochastic Modulation ◽  
And Task

AbstractSensory-guided behavior requires reliable encoding of stimulus information in neural responses, and task-specific decoding through selective combination of these responses. The former has been the topic of intensive study, but the latter remains largely a mystery. We propose a framework in which shared stochastic modulation of task-informative neurons serves as a label to facilitate downstream decoding. Theoretical analysis and computational simulations demonstrate that a decoder that exploits such a signal can achieve flexible and accurate readout. Using this theoretical framework, we analyze behavioral and physiological data obtained from monkeys performing a visual orientation discrimination task. The responses of recorded V1 neurons exhibit strongly correlated modulation. This modulation is stronger in those neurons that are most informative for the behavioral task and it is substantially reduced in a control condition where recorded neurons are uninformative. We demonstrate that this modulator label can be used to improve downstream decoding within a small number of training trials, consistent with observed behavior. Finally, we find that the trial-by-trial modulatory signal estimated from V1 populations is also present in the activity of simultaneously recorded MT units, and preferentially so if they are task-informative, supporting the hypothesis that it serves as a label for the selection and decoding of relevant downstream neurons.

scholarly journals Suboptimal eye movements for seeing fine details

2017 ◽  
Author(s):  
Mehmet N. Ağaoğlu ◽  
Christy K. Sheehy ◽  
Pavan Tiruveedhula ◽  
Austin Roorda ◽  
Susana T. L. Chung
Keyword(s):  
Eye Movements ◽  
Visual Target ◽  
Ganglion Cells ◽  
State Of The Art ◽  
Imaging Technique ◽  
Orientation Discrimination ◽  
Retinal Ganglion ◽  
Response Characteristics ◽  
Eye Motion ◽  
Human Eyes

AbstractHuman eyes are never stable, even during attempts of maintaining gaze on a visual target. Considering transient response characteristics of retinal ganglion cells, a certain amount of motion of the eyes is required to efficiently encode information and to prevent neural adaptation. However, excessive motion of the eyes leads to insufficient exposure to the stimuli which creates blur and reduces visual acuity. Normal miniature eye movements fall in between these extremes but it is unclear if they are optimally tuned for seeing fine spatial details. We used a state-of-the-art retinal imaging technique with eye tracking to address this question. We sought to determine the optimal gain (stimulus/eye motion ratio) that corresponds to maximum performance in an orientation discrimination task performed at the fovea. We found that miniature eye movements are tuned, but may not be optimal, for seeing fine spatial details.

scholarly journals Dynamics of Visual Adaptation With Simultaneous Stimulation of Two Visual Pathways

2021 ◽  
Vol 15 ◽  
Author(s):  
Clemente Paz-Filgueira ◽  
Michael Tan ◽  
Sarah Elliott ◽  
Dingcai Cao
Keyword(s):  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Visual Pathway ◽  
Visual Pathways ◽  
Visual Adaptation ◽  
Time Varying ◽  
Retinal Ganglion ◽  
Simultaneous Stimulation ◽  
Adaptation Model ◽  
Stimulation Of

Primates’ retinal ganglion cells in different visual pathways have been shown to adapt independently (Current Biology 22 (2012) 220–224). However, the manner in which adaptation occurs under simultaneous stimulation of two visual pathways has not yet been explored. In this study, the dynamics of color afterimages were measured while stimulating one or two visual pathway using a time-varying afterimage paradigm. The dynamics of adaptation was approximately equivalent among the three primary visual pathways, but adaptation was slower for simultaneous stimulation of two visual pathways compared to the stimulation of one visual pathway. In addition, we found that the speed of adaptation also depends upon which two pathways are combined. We developed a two-stage adaptation model, both with the same dynamics, to account for the results with simultaneous stimulation of two pathways.

Analysis of vertebrate eye movements following intravitreal drug injections. I. Blockade of retinal ON-cells by 2-amino-4-phosphonobutyrate eliminates optokinetic nystagmus

1988 ◽  
Vol 60 (3) ◽  
pp. 1010-1021 ◽  
Author(s):  
A. G. Knapp ◽  
M. Ariel ◽  
F. R. Robinson
Keyword(s):  
Visual Cortex ◽  
Eye Movements ◽  
Retinal Ganglion Cells ◽  
Optokinetic Nystagmus ◽  
Ganglion Cells ◽  
Directional Asymmetry ◽  
Retinal Ganglion ◽  
Binocular Stimulation ◽  
Vertebrate Eye ◽  
Stimulation Of

1. Horizontal optokinetic nystagmus (OKN) was examined in alert rabbits and cats following intravitreal injection of 2-amino-4-phosphonobutyrate (APB), an agent which selectively blocks the light-responsiveness of retinal ON-cells while having little effect on OFF-cells. The retinal actions of APB were assessed independently by electroretinography. 2. In five rabbits, doses of APB sufficient to eliminate the b-wave of the electroretinogram reduced drastically the ability of the injected eye to drive OKN at all stimulus speeds tested (1-96 degrees/s). Impairment of OKN was apparent within minutes of the injection, remained maximal for several hours, and recovered completely in 1-7 days. OKN in response to stimulation of the uninjected eye alone remained qualitatively and quantitatively normal. 3. Following administration of APB, OKN in response to binocular stimulation displayed a directional asymmetry. Stimuli moving in the preferred (temporal-to-nasal) direction for the uninjected eye became more effective than stimuli moving in the opposite direction, indicating that the injected eye could no longer contribute to binocular OKN. 4. When rabbits viewed stationary stimuli through the APB-treated eye alone, episodes of slow (less than 1 degrees/s) ocular drift were observed, similar to the positional instability seen when rabbits are placed in darkness or when the retinal image is stablized artifically (12). 5. APB had little effect on OKN in normal cats. In two cats that had previously received large lesions of the visual cortex, however, APB eliminated the ability of the injected eye to drive monocular OKN. The extent of the impairment was similar to that seen in rabbits. Because the cortex is thought to contribute more to OKN in cats than in rabbits, this result suggests that the optokinetic pathways disrupted by APB project subcortically. 6. This study demonstrates that the integrity of retinal ON-cells is required to sustain normal OKN. The results are consistent with additional anatomic and physiological evidence suggesting that a particular subclass of retinal ganglion cells, the ON-direction-selective cells, may provide a crucial source of visual input to central optokinetic pathways.

scholarly journals Normal Tension vs High Tension Glaucoma: An Overview

2019 ◽  
Vol 75 (2) ◽  
pp. 55-59
Author(s):  
Ján Lešták ◽  
Šárka Pitrová ◽  
Elena Nutterová ◽  
Libuše Bartošová
Keyword(s):  
Magnetic Resonance Imaging ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Visual Fields ◽  
Visual Pathway ◽  
Retinal Ganglion ◽  
Resonance Imaging ◽  
High Tension ◽  
Significant Difference ◽  
Fazekas Scale

The study provides an up-to-date overview of pathogenesis, functional and structural changes in normal tension glaucoma (NTG) and its differences from high tension glaucomas (HTG). The authors point to less known facts which make both diagnostic groups different. First of all, there are electrophysiological findings that verify pathology in the complete visual pathway in HTG in contrast to NTG where the retinal ganglion cell response is relatively normal but the abnormalities are in the visual pathway. This corresponds to the findings of functional magnetic resonance imaging of the brain with a significant decrease in activity in HTG compared to NTG. We found a higher decrease in activity in HTG following application of the colour paradigm compared to NTG where we did not see a similar difference. We also investigated the central corneal thickness (CCT) in both diagnostic groups. We did not find a statistically significant difference. However, we found the effect of CCT on progression of the changes in visual fields in HTG. In relation to suspicion of abnormally low cerebrospinal pressure and a possible cerebrovascular fluid flow disturbance in NTG, we examined the optic nerve thickness (OND) and optic nerve sheath diameter (OSD) at a distance of 4, 8, 16 and 20mm from the posterior pole of the eye. In the comparison with the healthy population, we did not find any abnormalities except for the width of the optic chiasma that was markedly lower in NTG. In relation to a possible impairment of cerebral perfusion we determined the degrees of cerebral atrophy using magnetic resonance imaging by measuring the bicaudate ratio (BCR) and white matter lesions using the Fazekas scale. We did not find a difference between HTG and NTG in BCR. We found statistically significant changes in BCR which correlated with the changes in visual fields. The higher values of the pattern defect were associated with increased brain atrophy (BCR). We did not detect similar relations in the Fazekas scale. We found a significant difference in this parameter among NTG, HTG and a control group. We found the most advanced changes in the patients with HTG. Conclusion: In HTG, impairment of retinal ganglion cells and subsequently also their axons, including visual cortex occurs because of a high intraocular pressure. In NTG, the retinal ganglion cells are relatively normal like the visual cortex, but alteration occurs in their axons. The cause is not a high intraocular pressure but most probably ischemia.

scholarly journals Transneuronal Degeneration in the Brain During Glaucoma

2021 ◽  
Vol 13 ◽  
Author(s):  
Mengling You ◽  
Rong Rong ◽  
Zhou Zeng ◽  
Xiaobo Xia ◽  
Dan Ji
Keyword(s):  
Visual Cortex ◽  
Ganglion Cells ◽  
Neuronal Damage ◽  
Current Knowledge ◽  
Retinal Ganglion ◽  
Optic Chiasma ◽  
Transneuronal Degeneration ◽  
Key Factor ◽  
Visual Cortex Neuron ◽  
Neuron Damage

The death of retinal ganglion cells (RGCs) is a key factor in the pathophysiology of all types of glaucoma, but the mechanism of pathogenesis of glaucoma remains unclear. RGCs are a group of central nervous system (CNS) neurons whose soma are in the inner retina. The axons of RGCs form the optic nerve and converge at the optic chiasma; from there, they project to the visual cortex via the lateral geniculate nucleus (LGN). In recent years, there has been increasing interest in the dysfunction and death of CNS and retinal neurons caused by transneuronal degeneration of RGCs, and the view that glaucoma is a widespread neurodegenerative disease involving CNS damage appears more and more frequently in the literature. In this review, we summarize the current knowledge of LGN and visual cortex neuron damage in glaucoma and possible mechanisms behind the damage. This review presents an updated and expanded view of neuronal damage in glaucoma, and reveals new and potential targets for neuroprotection and treatment.

scholarly journals Dynamic distortion of the orientation representational space after learning in the mouse primary visual cortex

2021 ◽  
Author(s):  
Julien Corbo ◽  
John P McClure ◽  
Orhan Batuhan Erkat ◽  
Pierre-Olivier Polack
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Processing ◽  
Sensory Integration ◽  
Orientation Discrimination ◽  
Stimulus Generalization ◽  
Behavioral Adaptation ◽  
V1 Neurons ◽  
Orientation Space ◽  
Representational Space

Learning is an essential cognitive mechanism that supports behavioral adaptation through neural processing adjustments. Learning was shown to modify sensory integration, yet the nature of those modifications and the computational advantages they confer remain unclear. By comparing the responses of primary visual cortex (V1) neurons evoked by oriented stimuli in naive mice and mice performing an orientation discrimination task, we found that the representations of rewarded and non-rewarded cues were sparser, more accurate and more stable in trained mice. This improved representation was associated with a distortion of the V1 orientation space such that stimuli close to the task cues were represented as the task stimuli themselves. This distortion was context-dependent, as it was absent in trained mice passively viewing the cues. Hence, visual processing in V1 was dynamically adapted to enhance the reliability of the representation of the learned cues and favor stimulus generalization in the task-relevant computational space.

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